Fertility of heifers after superovulation: the influence of eliminating the dominant follicle

The aim of this study was the estimation of reproduction parametrs of heife rs, donors of embryos after embryo collection, with regard to the influence of mechanical elimination of dominant follicles. Investigations were carri ed out on 55 heifers. A negative influence of mechanical removal of ovary d ominant follicels on the day superovulation began (10th day of oestrus cycl e) on the activity of ovaries and analysed parameters of reproduction was n ot determined. Average period between the day of embryo collection and firs t insemination totaled 61.9 days. In heifers that had the dominant follicle removed (group I), this period was about 21.3 days longer than in females, whose ovaries were not subjected to manipulations (group II). Remaining re production parameters i.e. the number of inseminations per heifers, the num ber of inseminations per conception, numbers of days from embryo collection to efficient insemination, conception rate and service interval were more positive in group I than in group II - i.e. respectively: 1.1; 1.3; 70.4; 8 7.5% and 2.3 days as compared to 1.8; 2.1; 95.3 days, 56.1% and 38.2 days. The percentage of heifers culled due to infertility in the compared groups of heifers was almost identical and amounted to 11.1% and 10.9% respectivel y in groups I and II. If 10 or more ova and embryos were collected from don or heifers, the tendency was for the period from embryo collection to the f irst insemination and conception to lengthen, as well as for the service pe riod, and a similar number of inseminations per heifers and per conception was observed in comparison to heifers producing less ova and embryos.